Existing systems typically take advantage of Global Positioning System (GPS) data to locate a user device and determine copresence with other user devices. However, GPS is power intensive and used infrequently, which results in a possibility of stale data. Moreover, the GPS hardware in some mobile devices is not accurate enough to provide a true copresence determination. In addition, if GPS is used indoors, the GPS signal may not be available and, as a result, the user device switches to using Wi-Fi or cellular means of location detection, which are much less accurate. Similarly, other copresence detection technologies, such as Bluetooth, audio, Wi-Fi, or the like, can be power intensive and would result in poor device battery life if constantly left running. Additionally, existing systems may be prone to spoofing (e.g., sending a fake coordinate to a server, etc.).